Isthmus of thyroid gland overlies the:

THYROID GLAND Normal weight of thyroid gland: 20-25 gms Isthmus that is located just inferior to the cricoid cailage, usually anterior to 2nd and 3rd (mainly) 4th tracheal rings. A pyramidal lobe is present in about 50% of patients. Thyroid capsule is condensed into the posterior suspensory or Berry's ligament near the cricoid cailage & upper tracheal rings. External laryngeal nerve runs close to the superior thyroid aery and the recurrent laryngeal nerve runs close to the inferior thyroid aery.